The invention relates generally to the field of ablation catheters, and in particular, to ultrasound-guided ablation catheters.
Physicians make use of catheters today in medical procedures that are best performed by gaining access into interior regions of the body. For example, in electrophysiological therapy, ablation is used to treat cardiac rhythm disturbances. Such a therapy may be used, for instance, to treat atrial fibrillation by forming long, thin lesions of different curvilinear shapes in heart tissue.
During these procedures, a physician steers a catheter through a main vein or artery into the interior region of the heart that is to be treated. An ablation element carried on the distal end of the catheter is positioned near the tissue that is to be ablated. For such treatments, the delivery of ablating energy must be closely governed to avoid incidence of tissue damage and coagulum formation. Further, the ablation catheters must be precisely positioned adjacent to and preferably in contact with the tissue to be treated, to insure the lesions are properly located.
Physicians and staff performing diagnostic and therapeutic procedures, such as electrophysiological therapy, typically require an imaging system to assist them in positioning the ablation catheter. Mini-transesophageal echocardiography (mini-TEE) probes are available, however, these probes must be swallowed or inserted down the patient's throat. Such probes are poorly tolerated by patients unless they are fully anesthetized. Further, these probes can be rather large (i.e., 20 French in diameter), use complex transducer configurations and may have difficulty in detecting tissue contact by the ablation elements.
Hence, it is desirable to provide an effective apparatus which assists the physician in determining whether the ablation elements are in contact with the tissue to be ablated. It is further desirable to have such imaging systems small enough to enter narrow and tortuous regions of the patient's vasculature. It is further desirable to have such imaging systems be located coincidental with the ablation elements to ensure tissue contact prior to ablation.